Term
Constitutional Abnormalities |
|
Definition
abnormalities that are present
in the conceptus or arise in the zygote, or very soon after the formation of the zygote. They are always present at birth (congenital). |
|
|
Term
|
Definition
arise from somatic cell mutations and are associated with malignancies. |
|
|
Term
Types of Chromosomal Abnormalities... |
|
Definition
1) Numerical
2) Structural |
|
|
Term
|
Definition
– Multiple phenotypic effects of (usually) a single gene. The term is used particularly when the effects are not obviously related. |
|
|
Term
Numerical Chromosomal Abnormalities |
|
Definition
- excesses of entire sets of chromosomes
- plus or minus individual chromosomes
|
|
|
Term
Structural Chromosomal Abnormalities |
|
Definition
|
- Rearrangements of chromosomes
-deletions
-duplications
-insertions
-inversions
-reciprocal translocations
- robertsonian translocations
|
|
|
Term
|
Definition
- thought to be caused mainly by mitotic failure in first division of the zygote, followed by another round of S-phase (DNA replication).
|
|
|
Term
Accuracy of Cytogenetic test depends on.... |
|
Definition
1) How many chromosomal bands are observed (banding resolution or level)
2) Number of Cells tested |
|
|
Term
|
Definition
1) Locus specific (or gene specific) probes detect small deletions (at kilobase level)
-For metaphase homologues
2)Repetitive sequence probes: Repetitive sequences include the satellite DNA sequences of centromeres and subtelomeric sequences
3) Whole chromosome paints
(Chromosome-specific painting probes)
|
|
|
Term
|
Definition
-In meiosis I, the failure of homologues to separate(disjoin)
-In meiosis II or mitosis, the failure of
sister chromatids to separate.
|
|
|
Term
|
Definition
|
The existence of two or more genetically different cell lines in the same individual
are formed postzygotically
|
|
|
Term
Robertsonian Translocations |
|
Definition
-only happens in acrocentric chromosomes
-Wholearm translocations of acrocentrics
Acrocentrics- 13, 14, 15, 16, 21, 22
|
|
|
Term
|
Definition
-translocation which cannot be detected by the banding patterns of the chromosomes involved
-detected by FISH whole paint choromosomes
|
|
|
Term
|
Definition
•can scan thousands of sequences from the genome.
•It specifies the copy number of each sequence, and can show deletions and duplications.
•The resolution of an array = how many sequences it includes, but always surpasses the resolution of the best cytogenetic preps, finding unsuspected abnormalities.
•But it cannot discover a balanced translocation.
|
|
|
